In Middleford, England, in 1892, underpaid variety show dancers Millicent Hopkins and her friend, Rose Bridges, go in search of a meal at the tailor shop of Rose's father. Mr. Hopkins disowned Millie when she became an actress, and now throws her and Rose out. While riding in a cab, Rose and Millie pass a political rally for liberal candidate Clive Loring, who seeks refuge in the cab when he is heckled. When Clive invites Millie and Rose to tea, they pretend to be ladies, and Clive is impressed with Millie's views on women's rights. The next day she attends his rally and misses her acting troupe's train. After she vows to give up acting, Millie's father reconciles with her. She spends the next day with Clive, and they fall in love. Clive's class-conscious older brother, Lord Belmont, convinces Millie that, for the sake of Clive's career, he must marry within his class, and she returns to the stage. One night, Millie tries to avoid seeing admirer Lord Montglyn after the show, and leaves with Rose while they are still in their stage makeup. When the women are mistaken for prostitutes by a constable, Millie accepts a stranger's offer to take refuge in his nearby apartment--number 17--which is Millie's lucky number. The man, Jose Martinez, turns out to be an accomplished pianist from Spain with a penchant for lavender perfume, who has become impoverished in England. Although Millie declines his advances, Jose maintains a good humor and plays one of Chopin's nocturnes for her. After hours of innocent conversation, Millie returns home. The next day, Jose is arrested for the murder of a moneylender named Edward Simpson, whom Jose had visited before he met Millie, and Millie is his only alibi. Clive, who has won a seat in Parliament, eventually locates Millie, and they marry. During a reception given by Lord Belmont, Rose warns Millie that the police are looking for her so that she can testify at Jose's murder trial. That night, Clive sees that Millie is disturbed by lavender-scented linens and questions her about it, but she denies its importance. The next morning, when a Scotland Yard detective named Carston visits, Millie denies knowing Jose. Lord Belmont, suspicious of Millie, attends the opening day of the trial and learns that the missing witness was superstitious about the number seventeen and liked Chopin's "Nocturne." At home that night, Lord Belmont tricks Millie into admitting those two facts, and she flees to Rose's apartment. Clive now believes Millie is guilty of improper behavior, and tells Rose that although his and Millie's marriage is over, Millie has a moral obligation to come forward to save Jose's life. Jose is found guilty, and on the day of his sentencing, Millie enters the courtroom. With Clive in the audience, Millie testifies that she spent an innocent night with Jose to escape the police. The confession makes headlines across London, and stuffy members of Parliament call for Clive's resignation. Clive defends Millie's character to them, and later finds Millie at her father's shop and asks her to return to him.